Some didn’t have a chance to flee. The Shiite oppression didn’t create ISIS, but it certainly did a share in helping recruitment.
The Iraqi regime will crumble, whether the Iranian mullahs really want to risk invading Iraq probably depends on how screwed up things get.
I agree with you completely on the Iraq government crumbling. There is nothing I have seen in the Abadi government that is far enough departure from Maliki to win over the Sunni tribes en mass. Perhaps some will. Further, Iraq’s budgets are pegged on a 90 USD per barrel. The barrel price is now 80 something. Which means they have revenue problem. As well, the oil production is off 25% because of areas under ISIS. This spells a huge potential for failure. Much of the 2015 budget will need to go into military spending... If they last that long